1. Field of the Invention
The present invention relates to an endoscope system provided with a filter for observation for special light which is insertable/retractable into and out of a light path for illumination light or a light path for observation light.
2. Description of the Related Art
Conventionally, in observations for special light such as an NBI (Narrow Band Imaging) observation which is an observation using a narrow band light, an infrared light observation which is an observation using an infrared light, and a fluorescence observation which is an observation using fluorescence, there was a possibility that a subject image has a lower brightness as compared to that obtained in a normal white light observation. For example, Japanese Patent Application Laid-Open Publication No. 10-151104 discloses a fluorescence endoscope apparatus which uses a so-called adjustable diaphragm which changes the size of diaphragm between in a white light observation and an observation for special light so that the observations can be performed in one endoscope by switching a white light and a special light.